The coast, also known as the coastline or seashore, is defined as the area where land meets the ocean, or as a line that forms the boundary between the land and the coastline. Shores are influenced by the topography of the surrounding landscape, as well as by water induced erosion, such as waves. The geological composition of rock and soil dictates the type of shore which is created. The Earth has around 620,000 kilometres (390,000 mi) of coastline. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor important ecosystems such as freshwater or estuarine wetlands, which are important for bird populations and other terrestrial animals. In wave-protected areas they harbor saltmarshes, mangroves or seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic species. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessile animals and various kinds of seaweeds. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore, representing the intertidal zone where there is one. Along tropical coasts with clear, nutrient-poor water, coral reefs can often be found between depths of 1–50 meters.
In physical geography, a fjord or fiord is a long, narrow inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Antarctica, British Columbia, Chile, Denmark, Egypt, Germany, Greenland, the Faroe Islands, Montenegro, Iceland, Ireland, Kamchatka, the Kerguelen Islands, Labrador, Newfoundland, New Zealand, Norway, Novaya Zemlya, Nunavut, Quebec, the Patagonia region of Argentina and Chile, Russia, South Georgia Island, Tasmania, Scotland and Washington state. Norway's coastline is estimated to be 29,000 km (18,000 mi) long with its nearly 1,200 fjords, but only 2,500 km (1,600 mi) long excluding the fjords.
Mean sea level is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datum – a standardised geodetic datum – that is used, for example, as a chart datum in cartography and marine navigation, or, in aviation, as the standard sea level at which atmospheric pressure is measured to calibrate altitude and, consequently, aircraft flight levels. A common and relatively straightforward mean sea-level standard is instead the midpoint between a mean low and mean high tide at a particular location.
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.
In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It often refers to those submerged ridges, banks, or bars that rise near enough to the surface of a body of water as to constitute a danger to navigation. Shoals are also known as sandbanks, sandbars, or gravelbars. Two or more shoals that are either separated by shared troughs or interconnected by past or present sedimentary and hydrographic processes are referred to as a shoal complex.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
A ria is a coastal inlet formed by the partial submergence of an unglaciated river valley. It is a drowned river valley that remains open to the sea.
An emergent coastline is a stretch along the coast that has been exposed by the sea by a relative fall in sea levels by either isostasy or eustasy.
In coastal geography, a concordant, longitudinal, or Pacific type coastline occurs where beds, or layers, of differing rock types are folded into ridges that run parallel to the coast. The outer hard rock provides a protective barrier to erosion of the softer rocks further inland. Sometimes the outer hard rock is punctured, allowing the sea to erode the softer rocks behind. This creates a cove, a circular area of water with a relatively narrow entrance from the sea.
Holderness is an area of the East Riding of Yorkshire, on the north-east coast of England. An area of rich agricultural land, Holderness was marshland until it was drained in the Middle Ages. Topographically, Holderness has more in common with the Netherlands than with other parts of Yorkshire. To the north and west are the Yorkshire Wolds. Holderness generally refers to the area between the River Hull and the North Sea. The Prime Meridian passes through Holderness just to the east of Patrington and through Tunstall to the north.
A raised beach, coastal terrace, or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin, mostly an old abrasion platform which has been lifted out of the sphere of wave activity. Thus, it lies above or under the current sea level, depending on the time of its formation. It is bounded by a steeper ascending slope on the landward side and a steeper descending slope on the seaward side. Due to its generally flat shape, it is often used for anthropogenic structures such as settlements and infrastructure.
Post-glacial rebound is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound and isostatic depression are phases of glacial isostasy, the deformation of the Earth's crust in response to changes in ice mass distribution. The direct raising effects of post-glacial rebound are readily apparent in parts of Northern Eurasia, Northern America, Patagonia, and Antarctica. However, through the processes of ocean siphoning and continental levering, the effects of post-glacial rebound on sea level are felt globally far from the locations of current and former ice sheets.
The Kingsbridge Estuary in the South Hams area of Devon, England runs from Kingsbridge in the north to its mouth at the English Channel near Salcombe and lies between Bolt Head and Sharpitor to the west and Portlemouth Down to the east. The estuary is some 8.6 kilometres (5.3 mi) in length, with numerous side channels. Several of its creeks have independent names, including Blanksmill, Frogmore, Southpool, Batson and Bowcombe Creek.
Coastal geography is the study of the constantly changing region between the ocean and the land, incorporating both the physical geography and the human geography of the coast. It includes understanding coastal weathering processes, particularly wave action, sediment movement and weather, and the ways in which humans interact with the coast.
In geomorphology a river is said to be rejuvenated when it is eroding the landscape in response to a lowering of its base level. The process is often a result of a sudden fall in sea level or the rise of land. The disturbance enables a rise in the river's potential energy, increasing its riverbed erosion rate. The erosion occurs as a result of the river adjusting to its new base level.
A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a narrow entrance. A fjord is an elongated bay formed by glacial action.
The coastline of the North Sea has been evolving since the end of the last ice age. The coastline varies from fjords, river estuaries to mudflats.
A fjard is a large open space of water between groups of islands or mainland in archipelagos. Fjards can be found along sea coasts, in freshwater lakes or rivers. Fjard and fjord were originally the same word with the general meaning of sailable waterway. In Scandinavia, fjords dominate along the North Sea coast while fjards dominate the Baltic Sea coast.
A steep coast is a stretch of coastline where the mainland descends abruptly into the sea. There is a sharp transition from the land to sea as opposed to that on a flat coast where the land descends gradually seawards. The height of the land on a steep coast is well above sea level.
The Goldthwait Sea was a sea that emerged during the last deglaciation, starting around 13,000 years ago, covering what is now the Gulf of Saint Lawrence and surrounding areas. At that time, the land had been depressed under the weight of the Laurentide Ice Sheet, which was up to 2 kilometres (1.2 mi) thick. Areas on the Anticosti Island and low-lying regions of Quebec and the Maritimes bordering the Saint Lawrence were below sea level. As the land rebounded over the next 3,000 years, despite rising sea levels the sea retreated to roughly the present boundaries of the Gulf.
